1. Field of the Invention
The present invention relates generally to an apparatus and method for dissolving a chemical in a liquid and more particularly for dissolving rock salt or calcium magnesium acetate (CMA) pellets in water for producing a salt solution of a specified concentration of salinity to be used as a liquid de-icer.
2. Description of the Related Art
Chemical solutions formed by dissolving a solid chemical in a liquid have been used in a variety of industrial applications, including the use of a salt solution for melting and removal of snow and ice from sidewalks, driveways, roadways, runways and the like. These solutions may be generally created by directing a liquid through an amount of the chemical to be dissolved, such as rock salt or CMA pellets, to produce a highly concentrated or saturated solution. The solution is then adjusted to a desired salinity for use on roadways. It has been found that a solution of 23.3% by weight is the most efficient solution for removing ice and snow (where sodium chloride is the salt). At this salinity level the solution will melt ice and snow with an ambient temperature of xe2x88x9211 degrees Fahrenheit. If the desired salinity is not maintained in the solution and applied in the correct amounts on the streets accidents may occur. It is desired to quickly and accurately produce large quantities of solution at a specified salinity for use by road maintenance crews to rid roadways of ice and snow. Highway maintenance crews typically store a large pile of salt, which must then be quickly and accurately added to a solution for loading trucks during and just after storms for road maintenance. Highway departments have heretofore had problems quickly producing large quantities of salt solutions at the desired salinity for best results.
Apparatus used for producing saline solutions for highway maintenance have used various methods for controlling the salinity. The methods include adding water to a tank filled with a salt. With the flow rates and tank measurements known approximations of the desired salinity can be achieved, however accurate salinity results are sacrificed in order to quickly produce a solution for immediate use.
Other apparatus for producing accurate saline solution include adding water to a batch of salt in a tank to create a high concentration of salt in solution and then adding water to the solution until the correct salinity is reached. It has been a problem to acheive this without a labor intensive apparatus, as measurements for salinity, adjustments to water flow rates, cleaning of screens to separate dirt and other particles form the salt solution and adding salt to the tanks have all been labor intensive steps.
The invention is an apparatus and method for automatically producing large quantities of dissolved rock salt or calcium magnesium acetate (CMA) pellets in water for producing a salt solution to be used as a liquid de-icer to be used for spraying roadways, sidewalks, driveways and runways to melt snow and ice.
A supply of rock salt or calcium magnesium acetate (CMA) pellets is stored in a hopper having an auger for feeding the salt or (CMA) into a hopper tank. The auger is operated automatically to add the salt or (CMA) when the hopper tank supply of salt or (CMA) is becoming low. Water is added to the hopper tank to dissolve the salt or (CMA) at the bottom of the hopper tank to create a flow of concentrated (100%) brine solution flowing from the hopper tank. The brine solution from the hopper tank then passed through cleaning strainers for removing sediment and other materials from the brine solution. Fresh water is added to the flow of brine solution and mixed therein. An electronic hydrometer (a specific gravity measuring device) measures the SG of the brine/water solution. If the specific gravity is too high or too low a valve is opened or closed to adjust the amount of fresh water to the mixture. In this manner the mixture is automatically adjusted to the salinity desired. The electronic hydrometer records the salinity of the mixture being produced. A sample of the mixture produced is measured for its temperature automatically by a digital thermometer as part of the specific gravity measurement. The saline solution produced is stored in a storage tank and then loaded into trucks for spreading on the streets to melt ice and snow.
Sediment and other material collected is sent in a stream of saline solution to a trash tank which is periodically cleaned out. The saline solution from the trash tank is filtered and sent to the hopper tank so that the trash tank does not overflow. The sediment and other material screened from the flow to the hopper tank is sent back to the trash tank.
It is an object of the invention to produce saline solutions with accurately controlled specific gravities.
It is an object of the invention to automatically add salt to a tank to continuously produce saline solutions with accurately controlled specific gravities.
It is an object of the invention to automatically remove contaminants from the saline solutions produced.
It is an object of the invention to automatically adjust the amount of water added to a saline solution to accurately control its specific gravity.
It is an object of the invention to automatically and continuously record the specific gravity of the saline solution being produced.
It is an object of the invention to reduce the labor required to make large quantities of saline solutions.